For an electronic device, such as a mobile phone, due to existence of positioning errors of a main board, patch errors of a card base, a manufacturing tolerance of a card holder and the like, an installation position of the card holder has an error, causing that the card try protrudes from a surface of the mobile phone and influencing an appearance of the mobile phone. Therefore, a protruding problem of the card holder must be solved by adjusting the patch position and making a short card holder. However, since sizes of the above errors and tolerance are uncertain, a protruding length of the card holder is uncertain. Therefore, adjusting positions of the patch and lengths of the card holder are different due to different situations, causing poor universality, complex operation and high improvement cost of the above method.